THIS is why they are different than you and I. This is why they are playing these games and we are watching them, why the tension of observing a playoff series is often so much worse on the fan than the player.

You take a walk through two clubhouses in the hours before a critical game – in this case, Game 6 of the Red Sox-Yankees American League Championship Series – and if you didn’t know what day it was, you’d swear it was the beginning of these baseball journeys, not the end. A breezy Florida morning, not a damp Northeastern evening.

“Nervous?” Red Sox first baseman Kevin Millar asked, as he entered Yankee Stadium last night, a few hours before the first pitch of Game 6. “Hell, what’s to be nervous about? You hope your whole life to play in games like this. I’ve played on some (lousy) teams where you played the whole month of September wondering if anyone was paying attention to you. Here, it feels like the whole country is watching.”

Millar chuckled.

“I mean, come on, what would you rather do?” he asked. “I ain’t getting any ulcers playing in these games.”

He may be the only one, of course.

In the hours after the Yankees seized a 3-0 lead in this best-of-seven series by thrashing the Sox 19-8 on Saturday, the emotions spilling out of Fenway Park were almost frightening to behold. Fans walked like zombies through the park’s narrow corridors, their eyes empty, their hearts frozen shut.

If you tuned in to WEEI radio, even in the wee hours, even as 3 a.m. approached, what you heard was a city avoiding the Christmas rush and beginning its winter mourning, its vigil toward season’s end. And as excited as the Fenway faithful were on Sunday and Monday, there were long stretches of the late innings when you thought all breathing had stopped in the grandstands and the bleachers.

OK, you could almost understand that in Boston, a place that has waited 85 years for a chance to fully enjoy October.

But how do you figure out New York? How do you figure out Yankees fans, who have known nothing but prosperity for almost all of those 85 years, who have enjoyed an especially curious dominance whenever they’ve needed to win a game against the Red Sox?

Yet if you talked to Yankees fans yesterday, if you listened to their fears and their loathings, you would have found a group of people who sounded amazingly, astonishingly, inexplicably, unconscionably like . . . like . . . like . . .

Well, just say it. Like Red Sox fans are supposed to sound.

They were roasting Joe Torre for the way he handled his bullpen, and for having his $17 million shortstop sacrificing late in the game. They were killing Alex Rodriguez for failing to get a man in from third with one out in the eighth. They were fretting over Curt Schilling’s impending Willis Reed moment. Depending on their level of sanity, some were even talking about getting physically ill just thinking of having to play the Red Sox again.

And God help them if there’s a Game 7.

“I waited my whole career to play in games that have this much meaning attached to them,” Yankees reliever Tom Gordon said last night. “Things haven’t gone the way I’d hoped. I haven’t been as effective as I expected I’d be. But I still want the ball. Tired? I’m not tired. Not now. Just excited. Spring training’s over now, you know? These are the games that matter most. These are the games you really want to play.”

That was the essence throughout the Yankees clubhouse, too. Maybe it makes sense that the Red Sox, those self-effacing “idiots,” were loose, since they were already playing with little to lose and now have only upside to play for. But the Yankees were the same way. It was all good.

“Let’s get out there right away,” Gordon said. “Let’s go. I’m ready. We all are.”